Hybrid graphene/silicon Schottky photodiode with intrinsic gating effect

By A. Di Bartolomeo, Giuseppe Luongo, Filippo Giubileo, N. Funicello, G. Niu, T. Schroeder, M. Lisker, G. Lupina. 2017

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We propose a hybrid device consisting of a graphene/silicon (Gr/Si) Schottky diode in parallel with a Gr/SiO2/Si capacitor for high-performance photodetection. The device, fabricated by transfer of commercial graphene on low-doped n-type Si substrate, achieves a photoresponse as high as 3  A W−1 and a normalized detectivity higher than 3.5×1012 cm Hz1/2  W−1  in the visible range. It exhibits a photocurrent exceeding the forward current because photo-generated minority carriers, accumulated at Si/SiO2 interface of the Gr/SiO2/Si capacitor, diffuse to the Gr/Si junction. We show that the same mechanism, when due to thermally generated carriers, although usually neglected or disregarded, causes the increased leakage often measured in Gr/Si heterojunctions. We perform extensive I–V and C-V characterization at different temperatures and we measure a zero-bias Schottky barrier height of 0.52 eV at room temperature, as well as an effective Richardson constant A**  =  4×10−5 A cm−2  K−2 and an ideality factor n≈3.6, explained by a thin (<1 nm) oxide layer at the Gr/Si interface.

Subfields: Atomic and Molecular Physics, and Optics, Electrical and Electronic Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/49ea3a70e28ed9fb8122cab9fe68f5bc3b190925